1. Field of the Invention
The invention relates to a dispersion powder composition which is redispersible in water and is based on water-insoluble polymers, process for its preparation and its use.
2. Background Art
Dispersion powder compositions which are redispersible in water and are based on homo- or copolymers are known. Such a dispersion powder composition is prepared by spray drying the corresponding aqueous plastics dispersions in a stream of hot air. The dispersion powders are suitable as additives to hydraulic binders in the building materials industry, and such products are furthermore employed as binders in coating compositions or in adhesives.
EP-A 228657 (U.S. Pat. No. 4,704,416) describes dispersion powders which are redispersible in water and are based on water-soluble polymers, and which comprise organic silicon compounds, preferably organopolysiloxanes. The dispersion powders are prepared by spray drying an emulsion of the organic silicon compound in an agueous solution of the water-soluble polymer.
EP-B 279373 relates to powders which are redispersible in water and comprise organopolysiloxane, and which additionally comprise a water-soluble, film-forming polymer. They are prepared by spray drying the acueous mixtures of the constituents mentioned.
EP-A 493168 relates to dispersion powders which are redispersible in water and are based on film-forming, waterinsoluble vinyl or acrylic polymers, and which comprise silicones, more precisely organosiliconates and/or organopolys-loxanes. They are prepared by sprav drying aqueous dispersions of the vinyl or acrylic polymers, to which silicones have been added before the spraying.